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Talk pages on mobile with Parsoid are unusable when there are level 1 headers
Closed, ResolvedPublicBUG REPORT

Description

Steps to replicate the issue (include links if applicable):

What happens?:
Sections cannot be expanded

What should have happened instead?:
Sections should be expandable and editable

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.): Opera mobile version 93.4.4906

Event Timeline

This is a regression that started yesterday after MediaWiki update.

Thanks for the report!

Can confirm this looks like a failure in patches for T416063, my recent changes on parsoid-mode section-opening setup during slow loading:

  • if the sections are visible during page load, while the user scrolls around the page, a JS handler adds the little disclosure triangles to each newly loaded top-level section heading and gives it a click handler
  • this does *not* appear to be working correctly for this particular NS_PROJECT page:
    • if I'm reading correctly it is indeed related to the <h1> headings on the page
      • the code is assuming that it has to hit <h2>-level headings IIRC, and it's obviously mismatching here

It looks like legacy will take <h1>s as the sections if they're present, otherwise uses the <h2>s? I'm going to have to double-check the exact behavior of the legacy parser mode and make sure I replicate it correctly when <h1>s are present. :D

bvibber added a subscriber: SherryYang-WMF.

@SherryYang-WMF is OOo today so I'm taking the liberty of sticking this regression in the queue for this sprint and assigning it to myself. I might not get to it today but it looks like a simple fix and I expect to be able to push a quick-fix patch monday.

Shouldn't explode anything too badly, other that painting some sections on certain page layouts with disclosure arrows that aren't clickable.

Change #1250639 had a related patch set uploaded (by Bvibber; author: Bvibber):

[mediawiki/extensions/MobileFrontend@master] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250639

Change #1250639 merged by jenkins-bot:

[mediawiki/extensions/MobileFrontend@master] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250639

Change #1250647 had a related patch set uploaded (by Bvibber; author: Bvibber):

[mediawiki/extensions/MobileFrontend@wmf/1.46.0-wmf.18] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250647

Change #1250648 had a related patch set uploaded (by Bvibber; author: Bvibber):

[mediawiki/extensions/MobileFrontend@wmf/1.46.0-wmf.19] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250648

Change #1250647 merged by jenkins-bot:

[mediawiki/extensions/MobileFrontend@wmf/1.46.0-wmf.18] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250647

Change #1250648 merged by jenkins-bot:

[mediawiki/extensions/MobileFrontend@wmf/1.46.0-wmf.19] Revert "Fix for temp section open during slow loads on Parsoid"

https://gerrit.wikimedia.org/r/1250648

Mentioned in SAL (#wikimedia-operations) [2026-03-11T20:10:19Z] <bvibber@deploy2002> Started scap sync-world: Backport for [[gerrit:1250647|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]], [[gerrit:1250648|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]]

Mentioned in SAL (#wikimedia-operations) [2026-03-11T20:12:29Z] <bvibber@deploy2002> bvibber: Backport for [[gerrit:1250647|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]], [[gerrit:1250648|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]] synced to the testservers (see https://wikitech.wikimedia.org/wiki/Mwdebug). Changes can now be verified there.

Mentioned in SAL (#wikimedia-operations) [2026-03-11T20:17:06Z] <bvibber@deploy2002> Finished scap sync-world: Backport for [[gerrit:1250647|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]], [[gerrit:1250648|Revert "Fix for temp section open during slow loads on Parsoid" (T416063 T419170 T419721)]] (duration: 06m 47s)

The patch has been reverted pending fixes...

Change #1251546 had a related patch set uploaded (by Bvibber; author: Bvibber):

[mediawiki/extensions/MobileFrontend@master] WIP Reworked fix for temp section open during slow loads on Parsoid

https://gerrit.wikimedia.org/r/1251546

@bvibber were you able to replicate this issue? I can't replicate it locally with https://gerrit.wikimedia.org/r/c/mediawiki/extensions/MobileFrontend/+/1251120 checked out.

The setup code did add the extra chevrons on the h2s, and the click code did fail on the h1 and thus not expand it. So I _think_ i've correctly replicated the issue, and the attached video is showing related error aftermath. :D

A locally duplicated page _seems_ to work correctly with the new patch on
https://gerrit.wikimedia.org/r/c/mediawiki/extensions/MobileFrontend/+/1251546
(page containing both <h1> and == headings)

Change #1251546 merged by jenkins-bot:

[mediawiki/extensions/MobileFrontend@master] Reworked fix for temp section open during slow loads on Parsoid

https://gerrit.wikimedia.org/r/1251546